Two classes of analysis systems are known in the field of medical analysis: wet analysis systems, and dry-chemical analysis systems. Wet analysis systems, which essentially operate using “wet reagents” (liquid reagents), perform an analysis via a number of required step such as, for example, providing a sample and a reagent into a reagent vessel, mixing the sample and reagent together in the reagent vessel, and measuring and analyzing the mixture for a measurement variable characteristic to provide a desired analytical result (analysis result). Such steps are often performed using technically complex, large, line-operated analysis instruments, which allow required manifold movements of participating elements. This class of analysis system is typically used in large medical-analytic laboratories.
On the other hand, dry-chemical analysis systems operate using “dry reagents” which are typically integrated in a test element and implemented as a “test strip”, for example. When these dry-chemical analysis systems are used, the liquid sample dissolves the reagents in the test element, and the reaction of sample and dissolved reagent results in a change of a measurement variable, which can be measured on the test element itself. Above all, optically analyzable (in particular colorimetric) analysis systems are typical in this class, in which the measurement variable is a color change or other optically measurable variable. Electrochemical systems are also typical in this class, in which an electrical measurement variable characteristic for the analysis, in particular an electrical current upon application of a defined voltage, can be measured in a measuring zone of the test element using electrodes provided in the measuring zone.
The analysis instruments of the dry-chemical analysis systems are usually compact, and some of them are portable and battery-operated. The systems are used for decentralized analysis, for example, at resident physicians, on the wards of the hospitals, and in so-called “home monitoring” during the monitoring of medical-analytic parameters by the patient himself (in particular blood glucose analysis by diabetics or coagulation status monitoring by warfarin patients).
In wet analysis systems, the high-performance analysis instruments allow the performance of more complex multistep reaction sequences (“test protocols”). For example, immunochemical analyses often require a multistep reaction sequence, in which a “bound/free separation” (hereafter “b/f separation”), i.e., a separation of a bound phase and a free phase, is necessary. According to one test protocol, for example, the probe can first be transported through a porous solid matrix, which contains a specific binding reagent for the analyte. A marking reagent can subsequently be caused to flow through the porous matrix, to mark the bound analyte and allow its detection. To achieve precise analysis, a washing step must previously be performed, in which unbound marking reagent is completely removed. Numerous test protocols are known for determining manifold analytes, which differ in manifold ways, but which share the feature that they require complex handling having multiple reaction steps, in particular also a b/f separation possibly being necessary.
Test strips and similar analysis elements normally do not allow controlled multistep reaction sequences. Test elements similar to test strips are known, which allow further functions, such as the separation of red blood cells from whole blood, in addition to supplying reagents in dried form. However, they normally do not allow precise control of the time sequence of individual reaction steps. Wet-chemical laboratory systems offer these capabilities, but are too large, too costly, and too complex to handle for many applications.
To close these gaps, analysis systems have been suggested which operate using test elements which are implemented in such a manner that at least one externally controlled (i.e., using an element outside the test element itself) liquid transport step occurs therein (“controllable test elements”). The external control can be based on the application of pressure differences (overpressure or low-pressure) or on the change of force actions (e.g., change of the action direction of gravity by attitude change of the test element or by acceleration forces). The external control is especially frequently performed by centrifugal forces, which act on a rotating test element as a function of the velocity of the rotation.
Analysis systems having controllable test elements are known and typically have a housing, which comprises a dimensionally-stable plastic material, and a sample analysis channel enclosed by the housing, which often comprises a sequence of multiple channel sections and chambers expanded in comparison to the channel sections lying between them. The structure of the sample analysis channel having its channel sections and chambers is defined by profiling of the plastic parts. This profiling is able to be generated by injection molding techniques or hot stamping. Microstructures, which are generated by lithography methods, increasingly being used more recently, however.
Analysis systems having controllable test elements allow the miniaturization of tests which have only been able to be performed using large laboratory systems. In addition, they allow the parallelization of procedures by repeated application of identical structures for the parallel processing of similar analyses from one sample and/or identical analyses from different samples. It is a further advantage that the test elements can typically be produced using established production methods and that they can also be measured and analyzed using known analysis methods. Known methods and products can also be employed in the chemical and biochemical components of such test elements.
In spite of these advantages, there is a further need for improvement. In particular, analysis systems which operate using controllable test elements are still too large. The most compact dimensions possible are of great practical significance for many intended applications.
U.S. Pat. No. 8,114,351 B2 discloses an analysis system for the analysis of a body fluid sample for an analyte. The analysis system provides a test element and an analysis instrument having a dosing station and a measurement station. The test element has a housing an (at least) one sample analysis channel enclosed by the housing. The test element is rotatable around an axis of rotation which extends through the test element.
U.S. Pat. No. 8,470,588 B2 discloses a test element and a method for detecting an analyte. The test element is essentially disk shaped and flat, and can be rotated about a preferably central axis which is perpendicular to the plane of the disk shaped test element.
Kim, Tae-Hyeong, et al. “Flow-enhanced electrochemical immunosensors on centrifugal microfluidic platforms.” Lab on a Chip 13.18 (2013): 3747-3754, doi:10.1039/c3Ic50374g, (hereafter “Kim et. al.”) discloses a fully integrated centrifugal microfluidic device with features for target antigen capture from biological samples, via a bead-based enzyme-linked immune-sorbent assay, and flow-enhanced electrochemical detection. This is integrated into a Centrifugal microfluidic discs, also known as “lab-on-a-disc” or microfluidic CDs.
Martinez-Duarte, Rodrigo, et al. “The integration of 3D carbon-electrode dielectrophoresis on a CD-like centrifugal microfluidic platform.” Lab on a Chip 10.8 (2010): 1030-1043, doi:10.1039/6925456K, (hereafter “Martinez-Duarte et. al.”) discloses a dielectrophoresis (DEP)-assisted filter with a compact disk (CD)-based centrifugal platform. 3D carbon electrodes are fabricated using the C-MEMS technique and are used to implement a DEP-enabled active filter to trap particles of interest.
International patent application WO 2014/041364 discloses a sample metering device for a liquid sample comprises at least one capillary passage with a first inlet for receiving sample, and an outlet; a side passage extending from the capillary passage part way along the length thereof and leading to the outlet; and a second inlet located between the first inlet and intersection with the side passage. A fluid application region for receiving a liquid sample to be tested is provided for entry to the capillary passage via the first inlet, and a second fluid application region is provided for entry of fluid such as chase buffer to the capillary passage. The second inlet prevents any excess sample in the well entering the capillary passage when chase buffer is applied.
United States patent application publication US 2013/0344617 A1 discloses a sample metering device for a liquid sample comprises at least one capillary passage with an inlet and an outlet; a side passage extending from the capillary passage part way along the length thereof and leading to an outlet; a fluid application region for receiving a liquid sample to be tested, for entry to the capillary passage via the inlet; first sealing means operable releasably to seal the outlet of the capillary passage; and second sealing means operable releasably to seal the outlet of the side passage.
United States patent application publication US 2012/0291538 A1 discloses a system and method for volumetric metering on a sample processing device. The system can include a metering reservoir, and a waste reservoir positioned in fluid communication with a first end of the metering reservoir to catch excess liquid from the metering reservoir that exceeds a selected volume. The system can further include a capillary valve in fluid communication with the second end of the metering reservoir to inhibit liquid from exiting the metering reservoir until desired. The method can include metering the liquid by rotating the sample processing device to exert a first force on the liquid that is insufficient to move the liquid into the capillary valve, and rotating the sample processing device to exert a second force on the liquid that is greater than the first force to move the metered volume of the liquid to the process chamber via the capillary valve.
United States patent application publication US 2004/011686 A1 discloses a nucleic acid refining apparatus, being ease in automation thereof, keeping high in contacting frequency between nucleic acid within a sample and a solid phase during nucleic acid capture processing, thereby proving high capturing rate, comprises: means for separating a liquid containing the nucleic acid therein from said sample through centrifugal force; means for transferring a reagent through the centrifugal force; means for producing a mixture liquid of said reagent transferred through the centrifugal force and a solution containing said nucleic acid therein; a carrier for capturing said nucleic acid; means for transferring said mixture liquid to said carrier through the centrifugal force; heating means for heating said carrier; and a holding means for separating and holding the reagent containing said nucleic acid eluting from said carrier.